Egg vitrification, an authentic revolution in assisted reproduction

Egg vitrification, more commonly known as egg freezing, is an authentic revolution in the assisted reproduction field. Not only for the purpose of preserving the fertility of women, but also for creating a large egg bank that will improve matching between donor and receiver in terms of time and increased options, in egg-donation treatments.

This technology is relatively new, but it has already been shown that the likelihood of pregnancy is the same in transfers of frozen and fresh eggs, with a success rate of 61% in donated egg treatments. That is because “a frozen egg behaves in exactly the same way as a fresh egg” says Albert Obradors, Eugin Clinic laboratory head.

In less than a second

Obradors, an embryologist who is in charge of the laboratory at Eugin Clinic, enthusiastically explains what vitrification consists of: it is a technique in which the eggs change from their usual temperature of 37º C to -200º C in less than a second. The change in temperature is so drastic and sudden that the water in the egg has no time to freeze and is vitrified, changing to a state that is similar to that of very hard “gelatine”.

This is the key to success, as if the water were frozen, tiny crystals would develop which could damage the interior of the egg, to the point of bursting it. Obradors provides the following graphic example: “It’s like filling a balloon with water and putting it in the freezer at home. It would most certain burst”.

The first important revolution was the freezing of embryos. This breakthrough was more than significant: previously, one out of every four embryos was unable to survive, but when they are frozen, only 8 out of every 100 eggs fail to survive. In 2005, this technology was taken a step further and used on eggs, opening up a wide range of opportunities in this field.

No time limit

The success of freezing eggs lies in the fact that their quality is maintained and they have no expiry date, meaning that they can be conserved for an unlimited period of time. The eggs do not age, and it is as if they were “suspended” until they are thawed. The many benefits of this technique in treatments with donated eggs include the possibility of having a second child from the same donor if the donor has frozen eggs, without having to wait for a new fresh egg cycle, since the donor may not be available at the required time.